U.S. patent application number 12/758751 was filed with the patent office on 2010-09-16 for fluidic lens with manually-adjustable focus.
This patent application is currently assigned to HOLOCHIP CORPORATION. Invention is credited to Robert G. Batchko, Andrei Szilagyi.
Application Number | 20100232031 12/758751 |
Document ID | / |
Family ID | 42730497 |
Filed Date | 2010-09-16 |
United States Patent
Application |
20100232031 |
Kind Code |
A1 |
Batchko; Robert G. ; et
al. |
September 16, 2010 |
FLUIDIC LENS WITH MANUALLY-ADJUSTABLE FOCUS
Abstract
A fluidic lens may have a transparent window member, a
transparent distensible membrane, an inner ring between the window
member and membrane, and a top ring disposed such that the membrane
is between the piston ring and the inner ring. A layer of liquid
may be stored between the window member, the inner ring and the
membrane. The top ring may be adapted to apply a liquid
displacement force to the membrane in a direction perpendicular to
a plane of an aperture of the inner ring to cause a change in a
radius of curvature of the membrane. The membrane may be
pre-tensioned prior to assembly with the other components.
Inventors: |
Batchko; Robert G.;
(Albuquerque, NM) ; Szilagyi; Andrei; (Danville,
CA) |
Correspondence
Address: |
JOSHUA D. ISENBERG;JDI PATENT
809 CORPORATE WAY
FREMONT
CA
94539
US
|
Assignee: |
HOLOCHIP CORPORATION
Hawthorne
CA
|
Family ID: |
42730497 |
Appl. No.: |
12/758751 |
Filed: |
April 12, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12117625 |
May 8, 2008 |
7697214 |
|
|
12758751 |
|
|
|
|
11383216 |
May 14, 2006 |
7646544 |
|
|
12117625 |
|
|
|
|
11747845 |
May 11, 2007 |
7672059 |
|
|
11383216 |
|
|
|
|
60916739 |
May 8, 2007 |
|
|
|
Current U.S.
Class: |
359/666 ;
359/665 |
Current CPC
Class: |
G02B 3/14 20130101 |
Class at
Publication: |
359/666 ;
359/665 |
International
Class: |
G02B 3/14 20060101
G02B003/14; G02B 3/12 20060101 G02B003/12 |
Claims
1-20. (canceled)
21. A fluidic lens, comprising: a chamber comprising an inner ring
disposed between first and second membranes; a fluid disposed at
least partially in the chamber; and a top ring disposed in
proximity to the chamber; wherein top ring is configured to be
brought into communication with at least a portion of the chamber;
wherein said communication results in a change in pressurization of
the fluid and deformation of at least one of the membranes.
22. The fluidic lens of claim 21 wherein at least a portion of at
least one of the first and second membranes is capable of elastic
deformation.
23. The fluidic lens of claim 21 wherein one or more of the first
or second membranes is at least partially transparent.
24. The fluidic lens of claim 21 further comprising a rotatable
member; wherein said rotatable member is disposed in communication
with one or more of the chamber or the top ring.
25. The fluidic lens of claim 24 wherein a rotation of rotatable
member results in said communication between the top ring and the
chamber.
26. The fluidic lens of claim 24 wherein one or more of the top
ring, chamber or rotatable member includes a threaded portion.
27. The fluidic lens of claim 21 further comprising a translatable
member; wherein said translatable member is disposed in
communication with one or more of chamber or top ring.
28. The fluidic lens of claim 27 wherein a translation of
translatable member results in said communication between top ring
and chamber.
29. The fluidic lens of claim 21 wherein the fluidic lens is part
of a telescope.
30. The fluidic lens of claim 21 wherein the fluidic lens is part
of an apparatus for testing vision.
31. The fluidic lens of claim 21, further comprising a surrounding
structure adapted to receive the chamber.
32. The fluidic lens of claim 21 wherein at least a portion of the
inner ring is deformable.
33. The fluidic lens of claim 21 wherein one or more of the
membranes is pre-tensioned.
34. The fluidic lens of claim 33 wherein the pre-tensioning of the
pre-tensioned membrane is sufficient to substantially overcome
aberrations resulting from gravity.
35. The fluidic lens of claim 21 wherein the fluidic lens is
adapted to interface with a lens mount.
36. The fluidic lens of claim 21 wherein the top ring is bonded to
one or more of the membranes.
37. The fluidic lens of claim 21 wherein the initial shape of one
or more of the membranes is substantially flat.
38. The fluidic lens of claim 21 wherein the initial shape of one
or more of the membranes is substantially convex.
39. The fluidic lens of claim 21 wherein the initial shape of one
or more of the membranes is substantially concave.
40. The fluidic lens of claim 21 further comprising an actuator
configured to actuate the top ring to bring the top ring into
communication with at least a portion of the chamber.
41. The fluidic lens of claim 40, wherein the actuator is selected
from the group of shape memory alloy actuators, electroactive
polymer actuators, electrostatic actuators, piezoelectric
actuators, stepper motors, voice coils, motor actuators and
electromagnetic actuators.
42. The fluidic lens of claim 21 wherein said communication results
in a change in pressurization of the fluid and change in optical
power of the fluidic lens.
43. The fluidic lens of claim 42 wherein the change in optical
power is positive or negative.
44. The fluidic lens of claim 21 wherein said communication results
in a change in pressurization of the fluid and change in curvature
of at least one of the membranes.
45. The fluidic lens of claim 44 wherein the top ring includes a
piston for communicating with the membrane; wherein the
communication between the top ring and membrane results in a
displacement of the membrane; and wherein the displacement is
approximately given by the relationship d = ( R - R 2 - r 1 2 ) 2
.times. ( 2 R + R 2 - r 1 2 ) ( r 1 + w ) 2 + ( r 1 + w ) .times. r
i + r i 2 ##EQU00008## wherein d=displacement; R=curvature of the
membrane; r.sub.1=inner radius of the top ring; r.sub.i=inner
radius of the inner ring; and w=width of the piston.
46. The fluidic lens of claim 21 wherein at least a portion of one
or more of the membranes is selected from the group of
silicone-based polymer, polyester material, PET and
biaxially-oriented polyethylene terephthalate.
47. The fluidic lens of claim 21 wherein at least a portion of the
fluid is substantially transparent.
48. The fluidic lens of claim 21 wherein at least a portion of the
fluid is selected from the group of silicone oil, bis-phenylpropyl
dimethicone, fluorinated polymer, and perfluorinated polyether.
49. The fluidic lens of claim 21 wherein at least a portion of one
or more of the membranes includes a window member.
50. The fluidic lens of claim 49 wherein the window member provides
one or more functions selected from the group of mechanical
protection, wavelength filtering, polarization filtering, and fixed
refraction.
51. A fluidic lens, comprising: a chamber comprising an inner ring
disposed between a membrane and a window; a fluid disposed at least
partially in the chamber; and a top ring disposed in proximity to
the chamber; wherein top ring is configured to be brought into
communication with at least a portion of the chamber; wherein said
communication results in a change in pressurization of the fluid
and deformation of at least one of the membranes.
Description
CLAIM OF PRIORITY
[0001] This application claims the benefit of priority of U.S.
Provisional Patent Application No. 60/916,739, filed May 8, 2007,
the entire contents of which are incorporated herein by reference.
This application is a continuation-in-part of and claims the
benefit of priority of U.S. patent application Ser. No. 11/383,216,
published as US Patent Application Publication 20070030573 A1, and
U.S. patent application Ser. No. 11/747,845, published as US Patent
Application Publication 20070263293, both of which are incorporated
herein by reference. The benefit of priority is also claimed to
U.S. Provisional Patent Applications 60/680,632, 60/683,072,
60/703,827, 60/723,381, and 60/747,181, the entire disclosures of
which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates generally to optics. More
particularly, it relates to fluidic optical devices.
BACKGROUND
[0003] Actuated fluidic lens structures are described in commonly
owned patent applications. These include U.S. patent application
Ser. No. 11/383,216, published as US Patent Application Publication
20070030573 A1, and U.S. patent application Ser. No. 11/747,845,
published as US Patent Application Publication 20070263293, both of
which are incorporated herein by reference, and U.S. Provisional
Patent Applications 60/680,632, 60/683,072, 60/703,827, 60/723,381,
and 60/747,181, the entire disclosures of which are incorporated
herein by reference. The predecessor of the present family of
devices is a fluid-filled chamber capable of squeezing transparent
fluid into a centrally-disposed elastic-membrane-delimited lens.
Pressurization of the fluid causes the membranes to bulge, thereby
controllably altering the optical power of the lens. The elastic
energy of the membranes provides the restoring force which
prevails, once the actuating force is diminished.
[0004] It is within this context that embodiments of the present
invention arise.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a cross-sectional diagram of a fluidic lens
according to an embodiment of the present invention.
[0006] FIG. 2 is a graph depicting membrane profiles for various
radii of curvature for a fluidic lens according to an embodiment of
the present invention.
[0007] FIG. 3 is a graph illustrating an effect of radius of
curvature on strain balancing in a fluidic lens membrane according
to an embodiment of the present invention.
[0008] FIG. 4 is a graph illustrating relationships between lens
radius and membrane anchor radius using extremes of strain
balancing.
[0009] FIG. 5 is a graph illustrating membrane profiles for fluidic
lenses with pistons of different widths.
[0010] FIG. 6 is a three-dimensional cut-away diagram of a manually
adjustable fluidic lens according to an embodiment of the present
invention.
SUMMARY OF THE INVENTION
[0011] According to embodiments of the present invention a fluidic
lens may have a transparent window member; a transparent
distensible membrane; an inner ring between the transparent window
member and the membrane; a layer of liquid stored between the
window member, the inner ring and the membrane; and a piston ring
disposed such that the membrane is between the piston ring and the
inner ring. The piston ring may be adapted to apply a liquid
displacement force to the membrane in a direction perpendicular to
a plane of an aperture of the inner ring to cause a change in a
radius of curvature of the membrane.
[0012] The piston ring may be characterized by an aperture radius
and an annular thickness, wherein the annular thickness is greater
than about 20%, 40%, 60%, 80%, or 100% of the annular radius. The
inner ring may have a conic frustum shaped inner surface
characterized by a half angle. The outer ring may also have a conic
frustum shaped outer surface characterized by a half angle that is
substantially the same as the half angle for the inner surface of
the inner ring.
[0013] An outer edge of the piston ring may be threaded. A
surrounding structure may be adapted to receive the inner ring,
membrane and piston ring, the surrounding structure having inner
threads that mate with the threads at the outer edge of the piston
ring.
DETAILED DESCRIPTION
[0014] As discussed above, actuated fluidic lens structures
described in commonly owned patent applications may be based on a
fluid-filled chamber capable of squeezing transparent fluid into a
centrally-disposed elastic-membrane-delimited lens. Pressurization
of the fluid causes the membranes to bulge, thereby controllably
altering the optical power of the lens. The elastic energy of the
membranes provides the restoring force which prevails, once the
actuating force is diminished. Embodiments of the present invention
are related to a family of fluidic optical devices with expanded
applicability.
[0015] A cross section of an embodiment of the present device
structure is illustrated in FIG. 1. A fluidic lens 100 may comprise
a ring shaped piston (piston ring or top ring) 102 that indents the
surface of a transparent membrane 104 which separates an inner
space filled with a liquid 105 from ambient air. Displacement of
the liquid 105--the liquid being essentially incompressible--causes
a central portion of the membrane 104 to bulge outwardly into an
energy-minimizing shape. In the case of a thin membrane, the
stretching of the membrane is associated with an increase in
hydrostatic pressure, for which the energy minimizing shape is a
simple spherical cap as seen in FIG. 1.
[0016] An immovable portion of the membrane 104 may be anchored
between an Outer Ring (not shown) and an Inner Ring 106. The inner
ring 106 has an inner surface that provides a lateral boundary for
the refractive fluid. In some embodiments, the Inner Ring 106 may
include one or more reservoirs in fluid communication with an
aperture region of fluidic lens 100. Examples of such
configurations are described, e.g., in US Patent Application
Publication 20070030573 and US Patent Application Publication
20070263292, both of which are incorporated herein by reference. As
shown in FIG. 1, the inner ring 106 may have a conic-frustum inner
surface 107, which forms a lateral boundary of the refractive fluid
105. The top ring 102 may have an outer edge with a conic-frustum
surface 103. The remaining fluid boundary may be provided by a Back
Window 108. In co-pending patent application Ser. No. 11/383,216
(Published as US Patent Application Publication 20070030573), the
Back Window is sometimes referred to as a Round Blank. The Membrane
104 may extend over an edge of the Back Window 108 as seen in FIG.
1. The Membrane 104 may be mechanically secured and hermetically
sealed to the Back Window 108, e.g., by an adhesive.
[0017] It will be clear to one skilled in the art that the above
embodiment may be altered in many ways without departing from the
scope of the invention. For example, the Back Window 108 (or at
least a portion thereof) may be made of a deformable, e.g.,
elastomeric or deformable polymer material and may act as a second
membrane in a manner similar to the transparent membrane 104.
Alternatively, the Fluidic Lens 100 may include an optional back
Membrane 104A. Examples of such configurations are described, e.g.,
in US Patent Application Publication 20070030573 and US Patent
Application Publication 20070263292, both of which are incorporated
herein by reference.
[0018] In some embodiments, the Inner Ring 106 may be made of a
rigid material, such as a metal or rigid polymer. Alternatively, in
some embodiments, the Inner Ring 106 (or at least a portion
thereof) may be made of a deformable material, e.g., an elastomer
or deformable polymer. If the Inner Ring 106 is deformable, an
outer diameter of the Top Ring 102 may be sufficiently large
compared to the outer diameter of the Inner Ring 106 that the Top
Ring 102 may press upon and deform the Inner Ring 106, thereby
exerting a displacement force on the Liquid 105. By way of example,
the Outer Diameter of the Top Ring 102 may be equal to or greater
than the Outer diameter of the Inner Ring 106. If the Inner Ring
106 includes a reservoir, some of the Liquid 105 may be expelled
from the reservoir into the aperture region of the Fluidic Lens 100
when the Top Ring 102 presses upon the Inner Ring 106, thereby
causing a displacement of the Membrane 104.
[0019] Also shown in FIG. 1, is an optional Front Window 110. In a
practical implementation, this front Window 110 may serve a number
of functions, such as mechanical protection of the elastomeric
membrane, wavelength or polarization filtering, additional fixed
refraction, etc. Such functions may alternatively be performed by
the Back Window 108.
[0020] Another feature visible in FIG. 1 is the presence of lead
screw threads 112 around the outer edges of the Top Ring 102. These
threads 112 may be configured to mate to corresponding threads on
an inner edge of a surrounding structure (not shown). When the Top
Ring 102 is rotated relative to the surrounding structure (or vice
versa), the mating threads on the surrounding structure (not shown)
cause the ring to advance or recede against the membrane 104, thus
adjusting the optical power of the fluidic lens 100.
[0021] The membrane 104 should be capable of stretching
elastically, should be durable enough to have a lifetime suitable
for its application. For example, in a cell phone camera
application the membrane 104 should have a lifetime of several
years and move than about one million cycles of operation. By way
of example, and without limitation, the membrane 104 may be made of
a silicone-based polymer such as poly(dimethylsiloxane) also known
as PDMS or a polyester material such as PET or Mylar.TM.
(biaxially-oriented polyethylene terephthalate). It is noted that
if the fluid 105 and membrane 104 have sufficiently similar
refractive indices, or include a suitable optical coating,
scattering of light at their interface can be significantly
reduced.
[0022] Examples of suitable materials for the membrane and
refractive fluid as well as examples of various schemes for
actuating the Piston Ring are described, e.g., in US Patent
Application Publication 20070030573, which has been incorporated
herein by reference. Among possible actuator solutions described
therein are shape memory alloy (SMA) actuators, Electroactive
Polymer (EAP) actuators also known as Electroactive Polymer
Artificial Muscle (EPAM) actuators, electrostatic actuators,
piezoelectric actuators, stepper motor, voice coil or other forms
of motor actuators and electromagnetic (EM) actuators. In addition,
certain forms of electrostatic actuator are described in U.S.
Patent Application Publication US Patent Application Publication
20070263293, which has been incorporated herein by reference.
[0023] By way of example, the fluid 105 may be silicone oil (e.g.,
Bis-Phenylpropyl Dimethicone). Additionally, fluid 105 may include
fluorinated polymers such as perfluorinated polyether (PFPE) inert
fluid. One example of a PFPE fluid is Fomblin.RTM. brand vacuum
pump oil manufactured by Solvay Solexis of Bollate, Italy. The
chemical chains of PFPE fluids such as Fomblin include fluorine,
carbon and oxygen and have desirable properties including low vapor
pressure, chemical inertness, high thermal stability, good
lubricant properties, no flash or fire point, low toxicity,
excellent compatibility with metals, plastics and elastomers, good
aqueous and non-aqueous solvent resistance, high dielectric
properties, low surface tension, good radiation stability and are
environmentally acceptable.
Calculation of Membrane Shape
[0024] In the design of a fluidic lens of embodiments of the
present invention it is useful to be able to relate the stroke d of
the Top Ring to the resulting membrane curvature, R. In the thin
membrane approximation, the desired formula may obtained from
equating the volume pushed-in by the piston to the volume of the
bulging membrane. The resulting equation is:
d ( R , r 1 ) := ( R - R 2 r 1 2 ) 2 ( 2 R + R 2 - r 1 2 ) ( r 1 +
w ) 2 + ( r 1 + w ) r i + r i 2 Eq . 1 ##EQU00001##
Where:
[0025] d=piston stroke
[0026] R=membrane curvature
[0027] r.sub.1=lens radius (clear aperture)
[0028] r.sub.i=radius of membrane anchor (Inner Ring)
[0029] w=radial width of piston portion of Top Ring
[0030] With this, the profile of the membrane may be plotted for
various radii of curvature, as in
[0031] FIG. 2. This profile is applicable as long as radius of the
membrane anchor is larger than the outer piston radius (r.sub.1+w).
Although this provides much design latitude, in practice, such a
device may need to be operated near the elastic limit of the
membrane.
Strain Balancing
[0032] To make design latitude as great as possible, it is
desirable to balance the strain in the inner (lens) and the outer
(conical portion) regions of the membrane.
[0033] When the strain in the spherical cap is set equal to the
strain in the conically-shaped outer portion of the membrane, the
ratio x of the membrane outer radius r.sub.i to the inner radius
r.sub.1 becomes constrained by the following equation:
x ( a , .rho. ) := [ ( 1 + a ) 3 + Rho ( .rho. ) ] 1 3 where : x =
r i r 1 a = w r 1 .rho. = R r 1 Rho ( .rho. ) := ( .rho. - .rho. 2
- 1 ) 2 ( 2 .rho. + .rho. 2 - 1 ) ( .rho. a sin ( 1 .rho. ) ) 2 - 1
Eq . 2 ##EQU00002##
[0034] The function Rho is fairly constant as the dimensionless
radius of curvature varies, except where R approaches r.sub.1, i.e.
the spherical cap approaches a hemispherical shape. This behavior
of Rho(.rho.) is illustrated in FIG. 3.
[0035] The asymptotic value of Rho is given by:
lim .rho. .fwdarw. .infin. Rho ( .rho. ) .fwdarw. 3 4 3 1 2 = 1.299
Eq . 3 ##EQU00003##
[0036] As can be seen from FIG. 3, the asymptotic value may be used
with less than 2% error for dimensionless radii of curvature down
to about 2. The other extreme is given by:
Rho ( 1 ) .fwdarw. 4 ( .pi. 2 - 4 ) 1 2 = 1.651 Eq . 4
##EQU00004##
[0037] These two extremes may be reflected in the strain balancing
(Equation 2):
x 0 ( a ) := [ ( 1 + a ) 3 + 3 3 4 ] 1 3 Eq . 5 a x 1 ( a ) := [ (
1 + a ) 3 + 4 ( .pi. 2 - 4 ) 1 2 ] 1 3 Eq . 5 b ##EQU00005##
[0038] To see graphically the effect of these strain balancing
choices on fluid lens design, the dimensionality of the membrane
outer radius may first be restored as follows:
r 0 i ( w , r 1 ) := r 1 x 0 ( w r 1 ) ##EQU00006## r 1 1 ( w , r 1
) := r 1 x 1 ( w r 1 ) ##EQU00006.2##
[0039] The resulting behavior is shown in FIG. 4. A piston width w
of 2 mm has been assumed for the purposes of example.
[0040] It is clear that the difference in membrane design between
these extreme cases is no more than a few percent in the region of
interest shown in FIG. 4. The reason these extremes are attenuated
so much is the presence of the cube root function in Equations 2,
5a and 5b. As a numerical example, when the clear aperture is 10 mm
and the radial piston width is 2 mm, the membrane outer radius (or
Inner Ring radius) varies by less than 3% when the strain is
balanced at either high or low radius of curvature:
r 1 i ( 2 mm , 5 mm ) r 0 i ( 2 mm , 5 mm ) = 1.028
##EQU00007##
Implementation of Strain Balancing
[0041] When strain balancing is implemented, the design of the
fluid lens may be optimized for various objectives. To illustrate
this, the membrane profile is graphically displayed in FIG. 5 in a
way that facilitates design trade-off between Top Ring stroke and
device footprint.
[0042] In FIG. 5, fluidic lens membrane profiles are shown for
lenses having pistons with different radial widths, thereby
illustrating the effect of piston radial width on membrane profile
It is noted that the lowest flat portion of each trace in FIG. 5
corresponds to the area where the piston face (e.g. the lower
portion of the top ring) contacts the membrane. A height of zero
designates a starting level of the membrane just before the Top
Ring piston impinges on it. In this approximation, the amount of
fluid initially contained in the lens is just sufficient to be
contained by a flat membrane. A similar analysis may be carried out
for alternatives where the initial membrane shape is either concave
or convex. Conversely, by bonding the piston face to the membrane,
it is possible to increase the achievable range of optical powers
to encompass both positive and negative curvatures. By way of
example, such bonding may be either adhesive based or may rely upon
attraction between a magnetized Top Ring and a thin annular
magnetic armature on the other side of the membrane. Either way,
the figure clearly demonstrates that a larger piston allows a
reduction in piston stroke for the same resulting optical power (or
membrane radius of curvature).
Practical Applications
[0043] FIG. 6 shows the cross section of a manually adjustable
fluidic lens 600 in accordance with an alternative embodiment of
the present invention.. In addition to the components first
introduced in relation to FIG. 1, the fluidic lens 600 additionally
includes a knurled Grip 602, bearing angular markings to be read
against a Reference marking 604. The Grip 602 is manually rotatable
by a user to adjust the optical power of the fluidic lens 600. The
Grip 602 is mounted in fixed relationship to an Outer Ring 606. The
Outer Ring 606, in turn, is slidably engaged with the Top Ring 102,
so that a pure rotation of the former results in combined rotation
and translation of the latter. The relative movement between the
Top Ring 102 and the Membrane '104 is one of pure translation,
whereby refractive adjustment is enabled without friction between
these components.
[0044] Numerous variations of this structure are possible without
departing from its essential inventive content. For instance, this
device may be interfaced to the user's optical system by means of
lens mounts engaging a Barrel portion 608 of the lens. This Barrel
608 may feature standardized threads, grooves or flats suitable for
mating features of the lens mounts.
[0045] Alternatively, screw threads may be provided to engage
mounting posts. One such thread is shown in FIG. 6 near the
Reference marking 604.
[0046] The force of gravity may present a challenge to fluidic lens
that is not normally associated with conventional lenses. In
particular, since the Fluidic Lens 100 is filled with a fluid, the
shape of the membrane 104 may depend on the orientation of lens
with respect to the force of gravity. Generally, gravity acts on
the fluid in a way that causes the fluid to exert a greater fluid
pressure on lower regions than on upper regions. The pressure
differential generally does not present a problem if the Fluidic
lens is held substantially horizontal. However, lenses are often
used in a vertical or tilted orientation. In such a situation, the
force of gravity acting on the Liquid 105 may lead to asymmetries
in the shape of the Membrane 104. For example, if the Fluidic lens
is oriented such that its optical axis is more or less horizontal,
lower portions of the may be more convex more than upper portions.
Such asymmetries may lead to lens aberrations, such as coma.
[0047] To counteract the effect of gravity on the liquid 105, the
Membrane 104 may be pre-tensioned to a degree sufficient to
counteract the effect of gravity. Pre-tensioning of the Membrane
104 may also serve to raise a resonant frequency of the Membrane
104 (and, hence of the Fluidic lens 100) thereby making them less
susceptible to transient aberrations due vibrations or acceleration
of the lens. The required degree of pre-tensioning may be
determined empirically by measuring optical aberrations or
susceptibility to vibration or acceleration as a function of
membrane pre-tensioning. Preferably, the pre-tensioning of the
Membrane is sufficient to overcome asymmetry in the shape of the
Membrane 104 when the Fluidic Lens 100 is in a vertical or tilted
orientation.
[0048] By way of example, and not by way of limitation, the
Membrane 104 may be pre-tensioned before assembly with the other
components of the Fluidic Lens 100. Specifically, the Membrane may
be placed over the Outer Ring 606. A tension may be applied to the
Membrane 104 in a radially symmetric fashion with respect to an
optical axis of the Fluidic Lens 100. The Inner Ring 106 may then
be placed on the Membrane 104 and the Liquid 105 may be placed in
the aperture of the Inner Ring 106. The Back Window 108 may then be
placed over the Inner Ring 106 with the Liquid 105 retained between
the Membrane 104, the
[0049] Inner Ring 106 and the Back Window 108. The Back Window 108
and Inner Ring 106 may then be pressed into the Outer Ring 606.
Adhesive may optionally be placed on the edge of the Back Window
108 prior to pressing to secure the Membrane 104 in place and
retain its pre-tensioned condition. Alternatively, the Membrane may
be held in place by friction between the Inner Ring 106 and Outer
Ring 606 if the fit between the Inner Ring 106 and the Outer Ring
608 is sufficiently tight.
[0050] Adjustable fluidic lenses according to embodiments of the
present invention may be used in numerous ways by optical
researchers, engineers and other users of optical systems. Other
uses include telescopes of civilian and military use, medical
systems such as used by optometrists to test the vision of
patients, etc.
[0051] Insofar as the description above and the accompanying
drawing disclose any additional subject matter that is not within
the scope of the single claim below, the inventions are not
dedicated to the public and the right to file one or more
applications to claim such additional inventions is reserved. Any
feature described herein, whether preferred or not, may be combined
with any other feature, whether preferred or not.
[0052] While the above is a complete description of the preferred
embodiment of the present invention, it is possible to use various
alternatives, modifications and equivalents. Therefore, the scope
of the present invention should be determined not with reference to
the above description but should, instead, be determined with
reference to the appended claims, along with their full scope of
equivalents. In the claims that follow, the indefinite article "A",
or "An" refers to a quantity of one or more of the item following
the article, except where expressly stated otherwise. The appended
claims are not to be interpreted as including means-plus-function
limitations, unless such a limitation is explicitly recited in a
given claim using the phrase "means for." Any feature described
herein, whether preferred or not, may be combined with any other
feature, whether preferred or not.
* * * * *